The transport of optical line data from an enterprise server to a remote device such as a storage device (such as to extend the storage area network to enable storage service providers to offer out-sourced storage services to the enterprise) is presently predominantly based on I/O channel protocols such as FC1, GbE and ESCON. However, these protocols were designed for in-building IT server room requirements and are not suitable for metropolitan (wide) area networks which extend over much greater distances. The use of these protocols over such greater distances imposes several challenges on the infrastructure of the metro area network including the need to accommodate Gbps transport rates with no packet loss and very low latency (delay).
At present such metro area networks (e.g. a metro DWDM transport network) are structured so as to assign an entire fiber wavelength to each data link in order to achieve low latency and high bandwidth. Disadvantageously, however, the cost of such networks is high and the number of customers they are able to serve is limited to the number of wavelengths deployed in the network. Other possible available options include the use of IP or ATM packet switching methods but IP switching inherently drops packets in an overload situation and, further, its transport protocols are relatively heavyweight. ATM switching is also of high cost and is not able to scale well in the Gbps data rate range required for storage traffic. Disadvantageously, the head of line blocking which results from the use of packet routers causes jitter at Gbps data rates. Further, if a normally switched SONET network is used it is necessary to include large realignment buffers at each end (to account for a differing delays incurred by different STS-1s due to different flow paths) and such buffers introduce undesirable latency (i.e. large transmission delays).
There is a need, therefore, for means to economically transport optical line data, such as from a fiber channel (FC) or Gigabit Ethernet (GbE) interface, over a metro or wide area link while achieving predictability with respect to the parameters (e.g. latency and bandwidth) of that link.